Science News Review

Eating Dirt: Research Finally Discovers A Reason!

Jan 11 at 6:06pm by Aileen

They call it “geophagy,” but we all know it as just plain dirt-eating. Dogs do it, horses do it, children do it regularly too. Now a study of chimpanzee dirt-eating by a research team from the Muséum National d’Histoire Naturelle in Paris has demonstrated actual health benefits of the practice.

Down to Earth Remedies for Chimps: Eat Mud reports that the research team collected samples of soil eaten by chimpanzees, along with samples of the plants they were eating at the same time and analyzed the material for bioactive properties. Moreover, they found that by ingesting a certain type of dirt along with the leaves of T. rubescens trees, anti-malarial properties in the leaves became active when they did not become active when ingested by themselves.

At the same time, the researchers compared the composition of soil eaten by these chimpanzees with soil used by traditional native healers in resident tribal communities to treat diarrhea, and found that the soil was rich in the mineral kaolinite – which is the principal component in some anti-diarrheal medicines.

The researchers discounted “old wive’s tales” that suggest dirt is ingested by animals who seek certain vitamins or minerals they aren’t getting in their diets, but their findings did tend to discount an opposite “old wive’s tale” that insists eating dirt is merely the behavior of the mentally unbalanced. While a compulsion to eat dirt may reflect unbalanced mental states, the commonality of the practice across species over evolution does reasonably suggest a reason.

Dirt can help expell intestinal parasites, but it can as often cause such parasites due to immature forms ‘hibernating’ in the soil. Dogs will often scratch up some good red clay and lick it, tending to indicate a need for iron in their diet (anemia is also a sign of parasites, and here the dirt may help solve both problems).

Expect more research to be undertaken in the future to try and understand behaviors that humans have dismissed as “animalistic” due to cultural prejudices, but which appear to be strongly conserved behaviors in evolution. Like carnivores (dogs, cats) who eat grass, feces and such. People who have dogs that love to raid the catbox not just for the chewy cat poop but also the crunchy clay litter clinging to it will tell you their dogs think it’s a taste treat sensation! Yucky though it seems to us, a reason for the behavior is better than simply assuming the poor dogs are crazy.

Down to Earth Remedies for Chimps: Eat Mud

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